Box levels of the type to which this invention pertains each include an elongate body which defines vial openings with plumb vials secured therein, a pair of spaced hand-hold openings, and in many cases hang openings near the opposite ends of the body to allow the levels to be hung on pegs or other hangers for storage purposes. The elongate bodies are typically of hollow box-like configuration. Such elongate bodies, of course, further define opposed first and second face planes, as well as narrower flat edge surfaces.
Each such box level also includes a pair of hand-holds, often of plastic and/or rubber-like material, lining the two hand-hold openings and secured in such openings to the elongate body. These two hand-holds have outer edges near each of the face planes of the elongate body—i.e., on either side of the elongate body. The outer edges of the two hand-holds on each side of the elongate body together define a parallel application plane just beyond the corresponding face plane. Thus, each hand-hold has first and second outer edges, and the first outer edges of the two hand-holds define an application plane just beyond the first face plane while the second outer edges of the two hand-holds define an application plane just beyond the second face plane.
These hand-holds provide, on each face of the box level, an appropriate reference plane for application of the box level against work surfaces the orientations of which are being determined. When rubber-like hand-holds are used, the level is resistant to slipping that may make surface gauging somewhat problematic.
Given that the outer edges of the hand-holds of such levels sometimes provide application-plane surfaces that are insufficient for application of the box-level against certain work surfaces (due to dimensional considerations), steps have been taken in product design to provide additional in-plane surface members near the ends of box levels—i.e., additional surface members having surfaces in the application planes.
In some cases, such additional in-plane surface-enhancing members are on or are part of end-caps which are engaged with (inserted into) the opposite ends of the elongate body—typically to cover the end edges of the elongate bodies themselves. While this is useful, end-caps are frequently susceptible to accidental removal or fall off because of how box levels are used or abused. This, of course, eliminates the reference surface enhancement for which they were designed, leaving the box levels with less-than-satisfactory ability to be accurately applied to certain work surfaces.
In other cases, special nubs or other elements are mounted to one of the face-forming walls of the elongate body, by snap engagement in specially formed holes in the walls or by other means. These elements not only involve extra machining of holes in the elongate body, but may also be knocked off. Examples of these and the above-described end-cap features in box levels are disclosed in U.S. Pat. No. 5,479,717.
There is a need for an improved box level overcoming the afore-mentioned problems and reliably providing improved reference surfaces to facilitate the effective application and use of box levels with respect to a wide variety of work surfaces.